I’m here today to ask for your advice regarding the sizing I’m planning for a temporary telecommunication installation, energy-autonomous for a few days.
Indeed, for temporary needs, we must plan to power telecommunication equipment, at 48v, continuously consuming 100 watts, for at least 4 days.
We plan to power this system with 3 12v LiFePO4 batteries (with integrated BMS) of 300AH, with possible reinforcement from a 200w solar panel.
This system must be able to be monitored remotely, but also via a local display.
This system, once used and discharged, must be able to be recharged within a maximum of 24 hours via the 230v electrical network and then go back into the field to serve again for 4 days.
Here is the diagram of what we thought would be suitable for our use:
Do you think we are headed in the right direction? Do you have any specific remarks? We have doubts about the choice of synchronized chargers and their ability to properly recharge our battery pack.
In any case, thank you for your feedback and experiences.
If it is not terribly fussy then You could vastly simplify the set up by using an inverter charger for your grid charging and use a 48v bank with bms comms and power it directly.
Mppt is a 100/20 or 150/35 with two panels for a slightly higher VOC. You will likely need a bit more solar than you have provisionally put there is grid dissapears for a few days.
Not sure how that costs out where you are located either. Just a different approach.
Thank you very much for your feedback, it’s very informative.
We need to provide a stable 48 to 52v to our telecommunications equipment.
Regarding the proposal for a battery directly in 48v (we don’t want to chain several 12v batteries in series), the prices are quite prohibitive for 900Ah of total capacity.
For solar, it’s really just a supplement to gain at best 2 days of autonomy in good weather.
Otherwise, regarding the rest of the diagram, have we made any errors in judgment?
Ah so you will still need a dc to dc for that if you used 48v
My thinking with the 48v was that it takes up less space than 12v.
I would personally would have added more solar possibly twice what you have, but as the spec says it’s temporary set up so would in theory just make the duration. Don’t forget there is also self consumption energy and conversion losses to allow for (and potentia6poor solar days). Hence the suggestion of one more panel.
The battery is 10.8kwh so the 100A phoenix would do that in 12 or 13 hours (allowing some derating for heat) so it does just meet spec.
Thanks again for you feedback, it’s crystal clear.
For solar panel, I have no space to have a bigger one or two panels : I only can use a 200w
Another question : what would be the best solution to cut off the power to each battery before the Lynx Power IN? we need to cut off the power to the whole system as close as possible to the batteries (for transport). Is there a switch with 3 inputs or …?
Thanks again for your valuable help, much appreciated.
You could use a mersen fuse disconnects then the users just pull fuses to the batteries after shutting down the rest of the system.
I do not know if you have any regulations where you are
We use AGM for telecoms UPS. The systems aren’t cycling every day so battery lifetime isn’t an issue. Also no BMS which will try to protect the batteries at the cost of the equipment they are supposed to be powering. Simpler system over all.
I’d also recommend a 48v system and using a Multiplus for your charger rather than Phoenix. Better integration with the Cerbo and batteries with BMS.
